Not all alien species in Ireland are invasive. Many are introduced purposefully to contribute to our economy, especially to the agriculture, forestry, and aquaculture industries. Although there is a variety of legislation designed to control the import of alien species to Ireland, some species can spread beyond their intended habitat which can lead to major negative impacts on biodiversity.
Other non-native (alien) species are bought to Ireland accidentally through human interference. Invasive plant species tend to spread through transportation of plant fragments or seeds, while invertebrates or mammals can move independently or hitch rides on vehicles, machinery, and freight.
Invasive species can transform ecosystems and threaten native species. The harm they cause to the economy and the environment is costly to repair.
Invasive alien species negatively impact Irish biodiversity through;
Competition – aliens can out-compete native species for food, water and space
Herbivory – introduced herbivores may affect native species by over-grazing or defoliating native plants
Predation – aliens can kill and/or eat native species
Habitat Alteration – aliens can change the natural structure of a habitat, making it unsuitable for native species
Introduction of parasites or pathogens – some alien species can be parasites or pathogens and therefore contribute to the spread of disease
Dilution of gene pools – alien species can weaken the gene pool (and reduce our biodiversity) if they interbreed with native species